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在 DbInterface 类中，函数 openDB() 打开与服务器上的 Oracle DB 的连接。出于安全原因，用户必须在 JFrame 文本区域中输入密码，然后程序才能继续连接。现在这个 Jframe 有一个动作监听器，它等待用户输入密码并调用 OpenDBContinue() 方法。

现在的问题是：openDB() 不会等待 Jframe IO 完成并假设 DB 已打开，将控制权返回给调用类（调用 openDB() 的人），然后他们继续开始查询显然失败的 DB！

现在如何让 openDB() 等待 Jframe IO 完成？这是给你一个想法的代码。

public void openDB(int inFileInx,String inRemoteDBURLFull) throws FileNotFoundException
{   
    if(this.password!=null)
        try
        {   openDBcontinue(inFileInx,inRemoteDBURLFull);
        }
        catch(Exception exp)
            {   DpmLogger.dtlException("SPDBInterfaceException:OpenDB", exp);
            }
    else {
            passwd  =       new JFrame();
            passwd.setLocation(SpdMain.bTabbedPanel.getWidth()/2,SpdMain.bTabbedPanel.getHeight()/2);
            passwd.setTitle("Enter Passwd for user "+username);
            JPasswordField p =new JPasswordField(10);
            p.addActionListener(this);
            p.setActionCommand(inFileInx+","+inRemoteDBURLFull);
            passwd.add(p);
            passwd.setPreferredSize(new Dimension(300,50));
            passwd.pack();
            passwd.setVisible(true);
            pass=new Thread(new Runnable()  
            {   
                public void run() {
                    DpmLogger.dtlTraceOut("The password thread has completed and has got password from the user",DpmLogger.TRACE_RARE,myId);
                }

            });

            try {
                    pass.join();
                } catch (InterruptedException e) 
                    {
                        DpmLogger.dtlTraceOut("Password thread unable to join",DpmLogger.TRACE_RARE,myId);
                    }

                DpmLogger.dtlTraceOut("Password thread now joined",DpmLogger.TRACE_RARE,myId);
        }

}


public void actionPerformed(ActionEvent e) 
{   JTextField p=(JTextField)e.getSource();
    if(password==null)
    password=p.getText();
    passwd.setVisible(false);

    String[] inVars=e.getActionCommand().split(",");
    try
    {   openDBcontinue(Integer.parseInt(inVars[0]),inVars[1]);
             pass.start();
    }
    catch(Exception exp)
    {   DpmLogger.dtlException("SPDBInterfaceException:OpenDB", exp);
    }
}

如您所见，我正在尝试使该方法在带有 join() 的“通过”线程上等待。当 IO 完成时，动作监听器启动 pass 线程。但它不起作用。OpenDB() 无需等待“通过”运行即可返回。这是因为该方法不在线程内吗？我必须让这个 DBInterface 类扩展 Thread 类吗？我很困惑！

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2 回答 2

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出于安全原因，用户必须在 JFrame 文本区域中输入密码

为了：

  1. 方便（和可能的解决方案）交换JFrame模态对话框或JOptionPane. EG 如this answer所示。
  2. 安全性使用 a而不是教程JPassWordField中看到的“textarea” 。
    在此处输入图像描述
于 2012-12-10T04:37:48.040 回答
3

You could use a JDialog, but that would require you to manage the close operations (add buttons and mess about with states), or you could simply use a JOptionPane

Either (when set to modal) will cause the Event Dispatching Thread to pause execution at that point until they are closed.

enter image description here

public class TestDialog01 {

    public static void main(String[] args) {
        new TestDialog01();
    }

    public TestDialog01() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                PasswordPane pane = new PasswordPane();
                int result = JOptionPane.showConfirmDialog(null, pane, "Password", JOptionPane.OK_CANCEL_OPTION, JOptionPane.QUESTION_MESSAGE);
                if (result == JOptionPane.OK_OPTION) {
                    // get the result...
                }

            }
        });
    }

    public class PasswordPane extends JPanel {

        private JTextField userName;
        private JPasswordField password;

        public PasswordPane() {
            userName = new JTextField(12);
            password = new JPasswordField(12);

            setLayout(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.insets = new Insets(2, 2, 2, 2);
            gbc.gridx = 0;
            gbc.gridy = 0;
            add(new JLabel("User Name:"), gbc);
            gbc.gridx++;
            add(userName, gbc);

            gbc.gridy++;
            gbc.gridx = 0;
            add(new JLabel("Password:"), gbc);
            gbc.gridx++;
            add(password, gbc);
        }

        public String getUserName() {

            return userName.getText();

        }

        public char[] getPassword() {

            return password.getPassword();

        }
    }
}

Check out How to Make Dialogs for more info

于 2012-12-10T04:45:14.987 回答